It is no secret that you can build your own robots and bionic limbs more affordably thanks to 3D printers. Take the Youbionic Arm for instance: it is a robotic limb that can perform all the movements of a human hand. It can be controlled by an Arduino and programmed on a PC or Mac.
You can buy the assembled version or 3D print its part yourself. Each hand has 6 active actuators and is powered by a 5V power bank.